Introduction :

Introduction Wireless Technology is an alternative to Wired Technology, which is commonly used, for connecting devices in wireless mode.
Wi-Fi (Wireless Fidelity) is a generic term that refers to the IEEE 802.11 communications standard for Wireless Local Area Networks (WLANs).
Wi-Fi Network connect computers to each other, to the internet and to the wired network.

IEEE 802.11a :

Slide 8:

Access point Adapters Components of Wi-Fi

Slide 9:

Wi-Fi Antenna Wi-Fi Bridge

Slide 10:

PCI cards that accept wireless PC cards External USB wireless NICs

How a Wi-Fi Network Works :

How a Wi-Fi Network Works Basic concept is same as Walkie talkies.
A Wi-Fi hotspot is created by installing an access point to an internet connection.
An access point acts as a base station.
When Wi-Fi enabled device encounters a hotspot the device can then connect to that network wirelessly.
A single access point can support up to 30 users and can function within a range of 100 – 150 feet indoors and up to 300 feet outdoors.
Many access points can be connected to each other via Ethernet cables to create a single large network. ?

Wi-Fi Network Topologies :

AP-based topology :

AP-based topology The client communicate through Access Point.
BSA-RF coverage provided by an AP.
ESA-It consists of 2 or more BSA.
ESA cell includes 10-15% overlap to allow roaming.

Peer-to-peer topology :

Peer-to-peer topology AP is not required.
Client devices within a cell can communicate directly with each other.
It is useful for setting up of a wireless network quickly and easily.

Point-to-multipoint bridge topology :

Point-to-multipoint bridge topology This is used to connect a LAN in one building to a LANs in other buildings even if the buildings are miles apart.These conditions receive a clear line of sight between buildings. The line-of-sight range varies based on the type of wireless bridge and antenna used as well as the environmental conditions.

Wi-Fi Security Threats :

Eavesdropping :

Eavesdropping Easy to perform, almost impossible to detect
By default, everything is transmitted in clear text
Usernames, passwords, content ...
No security offered by the transmission medium
Different tools available on the internet
Network sniffers, protocol analysers . . .
Password collectors
With the right equipment, it’s possible to eavesdrop traffic from few kilometers away

MITM Attack :

MITM Attack Attacker spoofes a disassociate message from the victim
The victim starts to look for a new access point, and the attacker advertises his own AP on a different channel, using the real AP’s MAC address
The attacker connects to the real AP using victim’s MAC address

Denial of Service :

Denial of Service Attack on transmission frequecy used
Frequency jamming
Not very technical, but works
Attack on MAC layer
Spoofed deauthentication / disassociation messages
can target one specific user
Attacks on higher layer protocol (TCP/IP protocol)
SYN Flooding

Wi-Fi Security :

Wi-Fi Security The requirements for Wi-Fi network security can be broken down into two primary components:
Authentication
User Authentication
Server Authentication
Privacy

802.1x Access Control :

802.1x Access Control Designed as a general purpose network access control mechanism
Not Wi-Fi specific
Authenticate each client connected to AP (for WLAN) or switch port (for Ethernet)
Authentication is done with the RADIUS server, which ”tells” the access point whether access to controlled ports should be allowed or not
AP forces the user into an unauthorized state
user send an EAP start message
AP return an EAP message requesting the user’s identity
Identity send by user is then forwared to the authentication server by AP
Authentication server authenticate user and return an accept or reject message back to the AP
If accept message is return, the AP changes the client’s state to authorized and normal traffic flows

Wireless Protected Access (WPA)(cont.) :

Wireless Protected Access (WPA)(cont.) WPA comes in two flavors
WPA-PSK
use pre-shared key
For SOHO environments
Single master key used for all users
WPA Enterprise
For large organisation
Most secure method
Unique keys for each user
Separate username & password for each user

WPA and Security :

WPA and Security Data is encrypted
Protection against eavesdropping and man-in-the-middle attacks
Denial of Service
Attack based on fake massages can not be used.
As a security precaution, if WPA equipment sees two packets with invalid MICs within a second, it disassociates all its clients, and stops all activity for a minute
Only two packets a minute enough to completely stop a wireless network Threats